Question

How much energy will be released from burning 230.0 g of liquid methanol (CH4O) in excess oxygen.

Answer 1

The molar mass of methanol is 12.01 + 4.04 + 16 = 32.05 g/mol
230.0 g of methanol / 32.05 g/mol = 7.176 mol methanol
The heat of combustion of methanol (CH3OH or CH4O) is -715.0 kJ/mol. (Negative sign means the energy is released)
Multiplying 7.176 mol by -715.0 kJ/mol gives -5,131 kJ.